Fan and cleaner

ABSTRACT

A fan includes an impeller rotated about the vertically extending central axis, a motor rotating the impeller, a motor housing housing the motor, and a fan casing disposed radially outside the motor housing to form a flow passage in a gap therebetween. A plurality of first stationary blades that axially extend and a second stationary blade that axially extends are disposed radially outside the motor housing. The first stationary blades are arranged in a circumferential direction. The second stationary blade is disposed between the first stationary blades adjacent to each other in the circumferential direction. An upper end of the second stationary blade is disposed further to a lower side than upper ends of the first stationary blades and further to an upper side than lower ends of the first stationary blades.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2017-099248 filed on May 18, 2017. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates to a fan and a cleaner.

2. Description of the Related Art

A centrifugal compressor includes a rotor, a diffuser, and a shroud.

The rotor has a shaft to which an impeller and a bearing cartridge are attached. The diffuser includes a hub, a circumstantial wall, a plurality of radial vanes and a plurality of axial vanes. The radial vanes are two-dimensional blades spaced apart from one another in the circumferential direction on an upper surface of the hub. The circumferential wall surrounds the hub with a gap therebetween. The axial vanes are two-dimensional blades extending between the circumferential wall and the hub. The rotor is rotatably attached to the diffuser by using the bearing cartridge. The shroud is attached to the diffuser so as to cover the impeller and the diffuser.

According to the centrifugal compressor, the radial vanes and the axial vanes are provided in respective different regions where air flows due to rotation of the impeller. This leads to reduction of the number of vanes in each of the regions, and accordingly, the gap between the adjacent vanes cannot be reduced in the circumferential direction. Thus, there is a possibility of reducing blowing efficiency.

SUMMARY OF THE INVENTION

According to an exemplary embodiment of the present disclosure, a fan includes an impeller rotated about the vertically extending central axis, a motor that rotates the impeller, a motor housing that houses the motor, and a fan casing disposed radially outside the motor housing so as to form a flow passage in a gap therebetween. A plurality of first stationary blades and a second stationary blade are disposed radially outside the motor housing. The first stationary blades are arranged in a circumferential direction and extend in an axial direction. The second stationary blade is disposed between the first stationary blades adjacent to each other in the circumferential direction, and the second stationary blade extends in the axial direction. An upper end of the second stationary blade is disposed further to a lower side than upper ends of the first stationary blades and further to an upper side than lower ends of the first stationary blades.

The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cleaner according to an embodiment of the present disclosure.

FIG. 2 is a perspective view of a fan according to the embodiment of the present disclosure.

FIG. 3 is a perspective view of the fan according to the embodiment of the present disclosure with a fan casing removed.

FIG. 4 is a longitudinal sectional view of the fan according to the embodiment of the present disclosure.

FIG. 5 is a sectional view of the fan according to the embodiment of the present disclosure with part of the fan casing cut off.

FIG. 6 is a graph illustrating an example of the relationship between the number of stationary blades and blowing efficiency in the fan according to the embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An exemplary embodiment of the present disclosure will be described below with reference to the drawings. Herein, a direction in which the central axis of a fan extends is referred to as “axial direction”, a direction perpendicular to the central axis of the fan is referred to as “radial direction”, and a direction along the arc centered at the central axis of the fan is referred to as “circumferential direction”. Furthermore, the above-described central axis is defined as an axis that extends in “vertical direction”, and herein, the suction side relative to an impeller is referred to as an “upper” side in description of the shapes and the positional relationships of components. However, the above-described “vertical direction” does not limit the positional relationships and directions when assembled in an actual apparatus. Furthermore, “upstream” and “downstream” referred to as those in the flowing direction of air sucked through an inlet when the impeller is rotated.

Furthermore, in a cleaner, a “lower” direction refers to a direction toward the floor and an “upper” direction refers to a direction separating from the floor in description of the shapes and the positional relationships herein. These directions are designations merely used for description, and these directions do not limit the actual positional relationships and the directions. Furthermore, “upstream” and “downstream” are referred to as those in the flowing direction of air sucked through an inlet when the fan is driven.

Herein, a cleaner according to the exemplary embodiment of the present disclosure is described. FIG. 1 is a perspective view of the cleaner according to an embodiment of the present disclosure. A cleaner 100 illustrated in FIG. 1 is a so-called stick-type electrical cleaner and includes a casing 102. The casing 102 has an inlet 103 and an outlet 104 formed in a lower surface and an upper surface thereof, respectively. A power cord (not illustrated) extends from a rear surface of the casing 102. The power cord is connected to a power outlet (not illustrated) provided in a side wall of a room, thereby the power is supplied to the cleaner 100. The cleaner 100 may be of a so-called robot type, a canister type, or a hand-held type electrical cleaner.

An air passage (not illustrated) that connects the inlet 103 and the outlet 104 to each other is formed in the casing 102. A dust collector (not illustrated), a filter (not illustrated), and a fan 1 are arranged in this order from the upstream side toward the downstream side in the air passage. Foreign matter such as dust contained in the air flowing through the air passage is blocked by the filter and collected in the dust collector having a container shape. The dust collector and the filter are removably mounted in the casing 102. Thus, a floor F can be cleaned.

A grip portion 105 and an operating portion 106 are provided in an upper portion of the casing 102. A user can move the cleaner 100 by holding the grip portion 105. The operating portion 106 includes a plurality of buttons 106 a. Operations of the cleaner 100 are set by operating the buttons 106 a. For example, the start and stop of drive, changes in rotational speed, and so forth of the fan 1 are instructed by operating the buttons 106 a. A downstream end (upper end in FIG. 1) of a rod-shaped suction pipe 107 is connected to the inlet 103. A suction nozzle 110 is detachably attached to an upstream end of the suction pipe 107.

Next, an overall structure of the fan 1 is described. FIG. 2 is a perspective view of the fan 1 according to the embodiment of the present disclosure. FIG. 3 is a perspective view of the fan 1 with a fan casing 2 removed. FIG. 4 is a longitudinal sectional view of the fan 1.

Roughly classified, the fan 1 includes the fan casing 2, an impeller 3, a motor housing 4, a motor 5, an upper bearing 6, a lower bearing 7, and a board 8. When the impeller 3 is rotated in a rotational direction R about a central axis C by the motor 5, the air is sucked into the fan casing 2 from the upper side and exhausted from the fan casing 2 toward the lower side.

The fan 1 includes the fan casing 2 having a cylindrical shape. The shape of the fan casing 2 is circular in the section in plan view. The fan casing 2 houses the impeller 3 and the motor housing 4. The fan casing 2 has an upper case portion 2A and a lower case portion 2B. The upper case portion 2A covers the impeller 3. The lower case portion 2B covers the motor housing 4. The upper case portion 2A and the lower case portion 2B may be an integrally formed single member or separately formed different members.

A bell mouth 21 is provided in an upper portion of the upper case portion 2A. The bell mouth 21 extends upward from an upper end and is bent inward. An inlet 211 that is an opening in the vertical direction is provided at the upper end of the bell mouth 21. The inlet 211 is positioned further to the upper side than an upper end of the impeller 3. An outlet 22 that is an opening in the vertical direction is provided at a lower end of the lower case portion 2B. In the cleaner 100, the fan 1 is disposed such that the inlet 211 faces the lower side (FIG. 1).

The impeller 3 includes molded resin components. The impeller 3 includes a base 31 and a plurality of blades 32. The diameter of the base 31 increases downward.

The base 31 has a boss portion 311 projecting downward. The boss portion 311 is connected to an upper portion of a shaft 53, which will be described later, by press fitting. The impeller 3 is rotated in the rotational direction R about the central axis C by the motor 5.

The plurality of blades 32 are arranged in the circumferential direction on an outer circumferential surface of the base 31. The blades 32 are integrally formed with the base 31. In each of the blades 32, an upper portion is disposed on a leading side relative to a lower portion in the rotational direction R. Thus, when the impeller 3 is rotated, the air sucked through the inlet 211 is guided in a direction directed toward the lower side and toward the leading side in the rotational direction R to a flow passage FL positioned further to the lower side than the impeller 3. The flow passage FL will be described later.

The motor housing 4 has an upper housing 41 and a lower housing 42. The upper housing 41 is disposed further to the upper side than the lower housing 42. The motor housing 4 houses therein the motor 5.

The upper housing 41 has a cup-shaped base portion 411. The base portion 411 has a cylindrical portion 4111 that is open at its lower portion and an upper lid portion 4112 positioned further to the upper side than the cylindrical portion 4111. The upper lid portion 4112 has a hole 4112A at the center thereof. The hole 4112A vertically penetrates through the upper lid portion 4112. The upper bearing 6 is secured to the upper lid portion 4112 at a lower portion of the hole 4112A. Although the upper bearing 6 includes a ball bearing, the upper bearing 6 may alternatively include another type of bearing such as a sleeve bearing.

An annular groove portion 4112B recessed downward is provided in an upper surface of the upper lid portion 4112. Here, an annular impeller projection 31A is provided on a lower surface of the base 31 of the impeller 3. At least part of the impeller projection 31A is accommodated in the groove portion 4112B. Thus, flowing of an airflow generated by the rotation of the impeller 3 to the inside of the impeller 3 (space SP) can be suppressed. That is, a labyrinth effect is produced so as to allow blowing efficiency of the fan 1 to be improved.

The cylindrical portion 4111 has a plurality of rod-shaped projections (not illustrated) on its inner circumferential surface. The rod-shaped projections radially inwardly project from the inner circumferential surface of the cylindrical portion 4111 and vertically extend. The rod-shaped projections have screw holes (not illustrated) that extend upward from lower ends thereof.

A plurality of first stationary blades 412 are arranged in the circumferential direction on an outer circumferential surface of the cylindrical portion 4111. The first stationary blades 412 extend in the axial direction. Furthermore, a plurality of second stationary blades 413 are arranged in the circumferential direction on the outer circumferential surface of the cylindrical portion 4111. The second stationary blades 413 are each disposed between the first stationary blades 412 adjacent to each other in the circumferential direction. The structure of the stationary blades will be described in detail later.

The lower housing 42 has a cup shape that is open at the upper side thereof. A bearing holding portion 421 is provided at the center of a bottom portion of the lower housing 42. The lower bearing 7 is held by the bearing holding portion 421. Although the lower bearing 7 includes a sleeve bearing, the lower bearing 7 may alternatively include another type of bearing such as a ball bearing.

A plurality of outlets 42A that are open in the vertical direction are disposed radially outside the bearing holding portion 421 at the bottom portion of the lower housing 42. The outlets 42A are arranged in the circumferential direction. As will be described later, the outlets 42A are openings through which the air having cooled a stator 51 is exhausted.

A plurality of base stage portions (not illustrated) are provided on an inner circumferential surface side of the lower housing 42. The base stage portions project radially inward. The base stage portions have screw holes (not illustrated) that vertically penetrate therethrough. The relationship between the base stage portions and the above-described rod-shaped projections will be described later.

The motor 5 housed in the motor housing 4 is disposed further to the lower side than the impeller 3. The motor 5 includes the stator 51, a rotor 52, and a shaft 53. The stator 51 includes the stator core 511, a plurality of coils, and insulators.

The stator core 511 is formed by vertically laminating electromagnetic steel plates. The stator core 511 includes an annular core back 5111 and a plurality of teeth (not illustrated). The plurality of teeth extend radially inward from an inner circumferential surface of the core back 5111, thereby forming a radial shape. The teeth have a substantially T-shape in plan view. The coils are wound around the teeth with the insulative insulators interposed therebetween.

In portions near the bottoms of the teeth, an inner circumferential surface and an outer circumferential surface of the core back 5111 are flat. This can prevent winding collapse of the coils. Furthermore, in portions other than the portions near the bottoms of the teeth, the inner circumferential surface and the outer circumferential surface of the core back 5111 are curved.

Inner surfaces of the above-described rod-shaped projections of the upper housing 41 include flat surfaces that are in contact with the flat portions of the outer circumferential surface of the core back 5111, and the upper housing 41 is placed on the lower housing 42. The rod-shaped projections of the upper housing 41 are placed on the base stage portions of the lower housing 42. The screw holes of the rod-shaped projections and the screw holes of the base stage portions are disposed in the vertical direction in a continuous manner. Bolts are screwed into these screw holes from the lower side. Thus, the upper housing 41 is secured to the lower housing 42 by the bolts.

In a state in which the upper housing 41 is secured to the lower housing 42, vent holes 411A that penetrate through the upper housing 41 in the radial direction are formed at positions that are adjacent to and on both sides of the rod-shaped projections of the cylindrical portion 4111 in the circumferential direction and that are further to the lower side than the first stationary blades 412 (FIG. 3). Effects of the vent holes 411A will be described later.

Furthermore, the curved portions of the outer circumferential surface of the core back 5111 are in contact with the curved inner circumferential surface of the cylindrical portion 4111 along the inner circumferential surface of the cylindrical portion 4111. That is, the stator core 511 is in direct contact with the upper housing 41.

The rotor 52 is disposed radially inside the stator 51. That is, the motor 5 is of a so-called inner-rotor type. The rotor 52 includes a plurality of magnets.

The shaft 53 that vertically extends is secured to the rotor 52. The shaft 53 is rotatably held by the upper bearing 6 and the lower bearing 7. An upper end portion of the shaft 53 is secured to the boss portion 311 of the impeller 3.

The discoidal board 8 is disposed further to the lower side than the lower housing 42. The board 8 includes a rigid board or a flexible board. Leads (not illustrated) extending from the coils of the motor 5 are electrically connected to a drive circuit (not illustrated) implemented on the board 8. Thus, the power can be supplied to the coils.

As illustrated in FIG. 4, the flow passage FL includes a space interposed between the outer circumferential surface of the upper housing 41 and an inner circumferential surface of the fan casing 2 and a space interposed between an outer circumferential surface of the lower housing 42 and the inner circumferential surface of the fan casing 2. The first stationary blades 412 and the second stationary blades 413 are disposed in the flow passage FL.

Here, for description of the structure of the stationary blades, FIG. 5 illustrates the fan 1 with part of the fan casing 2 removed so as to illustrate a section in which the stationary blades are visible. The first stationary blades 412 extending in the axial direction are arranged in the circumferential direction. The second stationary blades 413 extending in the axial direction are each disposed between the first stationary blades 412 adjacent to each other in the circumferential direction. Upper ends of the second stationary blades 413 are disposed further to the lower side than upper ends of the first stationary blades 412 and further to the upper side than lower ends of the first stationary blades 412.

With this structure, the air sucked through the inlet 211 due to the rotation of the impeller 3 flows into the flow passage FL from an upper end of the flow passage FL and is sent to the first stationary blades 412. The air flowing toward spaces between the first stationary blades 412 adjacent to one another in the circumferential direction is guided through the spaces between the first stationary blades 412. Then, part of this air is guided through spaces between pressure surfaces PS1 of the first stationary blades 412 and suction surfaces MS2 of the second stationary blades 413, and the other part of this air is guided through spaces between suction surfaces MS1 of the first stationary blades 412 and pressure surfaces PS2 of the second stationary blades 413. Here, the pressure surfaces refer to surfaces on trailing sides of the stationary blades in the rotational direction R of the impeller 3, and the suction surfaces refer to surfaces on leading sides of the stationary blades in the rotational direction R of the impeller 3.

The air guided through the stationary blades is discharged to the outside through the outlet 22 at a lower portion. Here, arrows illustrated in FIG. 4 indicate flows of the air. As described above, since the airflow is regulated by the first stationary blades 412 and the second stationary blades 413 so as to blow the air, the blowing efficiency can be improved.

That is, the fan 1 according to the present embodiment includes the impeller 3 rotated about the vertically extending central axis C, the motor 5 that rotates the impeller 3, the motor housing 4 that houses the motor 5, and the fan casing 2 that is disposed radially outside the motor housing 4 so as to form the flow passage FL in the gap therebetween. The plurality of first stationary blades 412 and the second stationary blades 413 are disposed radially outside the motor housing 4. The first stationary blades 412 are arranged in the circumferential direction and extend in the axial direction. The second stationary blades 413 are each disposed between the first stationary blades 412 adjacent to each other in the circumferential direction, and the second stationary blades 413 extend in the axial direction. The upper ends of the second stationary blades 413 are disposed further to the lower side than the upper ends of the first stationary blades 412 and further to the upper side than the lower ends of the first stationary blades 412.

Thus, a large number of the stationary blades can be disposed in a particular region of the flow passage FL, and accordingly, the spacing between the stationary blades in the circumferential direction can be reduced. Accordingly, efficiency of blowing due to the airflow caused by the rotation of the impeller 3 can be improved. FIG. 6 illustrates an example of the relationship between the number of the stationary blades and the blowing efficiency. According to the present embodiment, 13 of the first stationary blades 412 and 13 of the second stationary blades 413 are provided, that is, a total of 26 of the stationary blades are provided. It can be understood that, as the number of the stationary blades increases, the blowing efficiency improves as illustrated in FIG. 6.

Furthermore, as illustrated in FIG. 5, lower ends of the second stationary blades 413 are disposed at a lower position than the lower ends of the first stationary blades 412. This allows the second stationary blades 413 to guide the air also at regions further to the lower side than the lower ends of the first stationary blades 412. Accordingly, compared to the case where only the first stationary blades 412 are disposed, the blowing efficiency can be improved.

Furthermore, the first stationary blades 412 at least partially superpose on the second stationary blades 413 when seen in the axial direction. This allows the first stationary blades 412 and the second stationary blades 413 to be disposed in particular regions of the flow passage FL in the circumferential direction. Thus, more stationary blades can be disposed, and accordingly, the blowing efficiency can be improved.

Furthermore, as has been described, the stator core 511 is in direct contact with the upper housing 41. Here, when the upper housing 41 is formed of, for example, metal, the first stationary blades 412 and the second stationary blades 413 are formed of metal. That is, at least part of the motor 5 is in direct contact with the motor housing 4, and the first stationary blades 412 and the second stationary blades 413 are metal members.

Thus, the rigidity of the stationary blades, which are metal members, can be improved. Furthermore, heat is conducted from the motor 5 to the stationary blades due to thermal conduction and dissipated from the stationary blades into the air due to thermal transfer. When the stationary blades are metal members, the thermal conductivity of the stationary blades is improved. This can improve the cooling characteristics of the motor 5. The stator core 511 and the motor housing 4 may be in contact with each other with, for example, another member interposed therebetween. That is, the at least part of the motor 5 may be in indirect contact with the motor housing 4. In this case, the other member described above is preferably formed of a material having high thermal conductivity.

Furthermore, as has been described, for example, the number of the first stationary blades 412 is 13, and the number of the second stationary blades 413 is 13. That is, the number of the first stationary blades 412 is equal to the number of the second stationary blades 413. Thus, the stationary blades can be equally distributed in the circumferential direction, and accordingly, generation of turbulent flow can be suppressed and blowing efficiency can be improved.

Furthermore, in the circumferential direction, the thickness of the second stationary blades 413 is smaller than the thickness of the first stationary blades 412. Thus, compared to the case where the thickness of the second stationary blades 413 is large, the width of parts of the flow passage FL defined by the first stationary blades 412 and the second stationary blades 413 adjacent to one another in the circumferential direction can be increased in a region of the flow passage FL where the second stationary blades 413 are disposed. This allows the sectional area of the flow passage to be increased in a region where the first stationary blades 412 and the second stationary blades 413 are disposed in the flow passage FL. Accordingly, the blowing efficiency can be improved.

Furthermore, a first lower curved surface CS1, which is curved toward the leading side in the rotational direction R of the impeller 3 as it extends downward, is formed in a lower end portion of the pressure surface PS1 of each of the first stationary blades 412, and a second lower curved surface CS2, which is curved toward the leading side in the rotational direction R of the impeller 3 as it extends downward, is formed in a lower end portion of the pressure surface PS2 of each of the second stationary blades 413. The radius of curvature of the second lower curved surface CS2 is larger than the radius of curvature of the first lower curved surface CS1.

Thus, the lower end portion of the first stationary blade 412 having a large thickness in the circumferential direction is curved more. This can suppress separation of the air flowing downward along the first lower curved surface CS1 at a position immediately below the first stationary blade 412. Accordingly, generation of turbulent flow immediately below the first stationary blade 412 can be suppressed.

Preferably, the radius of curvature of the second lower curved surface CS2 is 1.8 to 2.5 times the radius of curvature of the first lower curved surface CS1. This can suppress the occurrence of a situation in which the air flowing along the pressure surface PS1 of the first stationary blade 412 strikes the pressure surface PS2 of the second stationary blade 413 when this air is guided along the first lower curved surface CS1 from the lower end of the first stationary blades 412 toward the leading side in the rotational direction R. Thus, generation of turbulent flow at a region further to the lower side than the first stationary blade 412 and the second stationary blade 413 can be suppressed, and accordingly, the airflow can be uniformed as much as possible.

Furthermore, the first stationary blade 412 includes a first stationary blade upper portion 4121 and a first stationary blade lower portion 4122. The first stationary blade upper portion 4121 is inclined toward the circumferential direction toward a trailing side in the rotational direction R of the impeller 3 as it extends from the lower side toward the upper side. The first stationary blade lower portion 4122 is positioned further to the lower side than the first stationary blade upper portion 4121 in the axial direction. The second stationary blade 413 includes a second stationary blade upper portion 4131 and a second stationary blade lower portion 4132. The second stationary blade upper portion 4131 is inclined toward the circumferential direction toward the trailing side in the rotational direction R of the impeller 3 as it extends from the lower side toward the upper side. The second stationary blade lower portion 4132 is positioned further to the lower side than the second stationary blade upper portion 4131 in the axial direction.

Thus, the air exhausted toward the leading side of the rotational direction R of the impeller 3 can be smoothly guided downward in the axial direction along the first stationary blade upper portion 4121 and the second stationary blade upper portion 4131. Accordingly, the blowing efficiency can be improved.

The first stationary blade upper portion 4121 has a first pressure curved surface 4121A curved on the pressure surface PS 1 side and a first suction curved surface 4121B curved on the suction surface MS1 side. Furthermore, the second stationary blade upper portion 4131 has a second pressure curved surface 4131A curved on the pressure surface PS2 side and a second suction curved surface 4131B curved on the suction surface MS2 side.

That is, the first stationary blade upper portion 4121 has first curved surfaces (4121A and 4121B) curved further toward the trailing side than the first stationary blade lower portion 4122 in the rotational direction R of the impeller 3, and the second stationary blade upper portion 4131 has second curved surfaces (4131A and 4131B) curved further toward the trailing side than the second stationary blade lower portion 4132 in the rotational direction R of the impeller 3.

Thus, the air can be smoothly guided by the first curved surfaces and the second curved surfaces. Accordingly, the blowing efficiency can be improved. In the upper portion of each of the stationary blades, it is sufficient that the curved surface be formed on at least one of the pressure surface side and the suction surface side. For example, an inclined surface as a not-curved flat surface may be formed on either of the pressure surface side and the suction surface side.

Furthermore, when L1 is a length in the circumferential direction between a trailing end of the first stationary blade 412 in the rotational direction R of the impeller 3 and a leading end of the first stationary blade upper portion 4121 on the pressure surface PS1 in the rotational direction R of the impeller 3, and L2 is a length in the circumferential direction between a trailing end of the second stationary blade 413 in the rotational direction R of the impeller 3 and a leading end of the second stationary blade upper portion 4131 on the pressure surface PS2 in the rotational direction R of the impeller 3, L1 is larger than L2.

Thus, the curved surface 4121A of the pressure surface PS1 of the first stationary blade upper portion 4121 is largely curved. Accordingly, the airflow can be guided downward by the first stationary blade 412, and the airflow having been guided by the first stationary blade 412 can be further guided downward by the second stationary blade 413.

Furthermore, the radius of curvature of the pressure surface in one of the first curved surfaces (4121A) is smaller than the radius of curvature of the pressure surface in one of the second curved surface (4131A). Thus, the air having a rotating component toward the leading side in the rotational direction R of the impeller 3 can be guided downward in the axial direction by the first stationary blade upper portion 4121. Accordingly, the blowing efficiency can be improved. It is particularly preferable that the radius of curvature of the pressure surface in the second curved surface be 1.8 to 2.2 times the radius of curvature of the pressure surface in the first curved surface.

Furthermore, the second stationary blade lower portion 4132 has an extended surface S21. The extended surface S21 extends in the axial direction at a position further to the lower side than the lower end of the first stationary blade 412 on the pressure surface PS2 side. Thus, the air guided by and separated from the first stationary blade 412 is smoothly guided downward along the extended surface S21. This can suppress separation of the air having been separated from the first stationary blade 412 from the second stationary blade 413. Accordingly, the blowing efficiency can be improved.

Furthermore, the first stationary blade lower portion 4122 has a first surface S1 that extends in the axial direction on the pressure surface PS1 side, and the second stationary blade lower portion 4132 has a second surface S2 that extends in the axial direction on the pressure surface PS2 side. The axial length of the first surface S1 is smaller than the axial length of the second surface S2. The extended surface S21 is included in the second surface S2. Thus, since the length of the second surface S2 is large in the axial direction, separation of the airflow that has been redirected by the first stationary blade 412 to flow in the axial direction from the second stationary blade 413 can be suppressed. Accordingly, the blowing efficiency can be improved. It is particularly preferable that the axial length of the second surface S2 be 0.2 to 0.65 times the axial length of the second stationary blade lower portion 4132.

Furthermore, the axial length of the second stationary blade upper portion 4131 is preferably 0.2 to 0.5 times the axial length of the second stationary blade 413. Thus, the airflow is guided downward in the axial direction by the second stationary blade upper portion 4131. Accordingly, the blowing efficiency can be improved.

Furthermore, in the circumferential direction, in a region where the first stationary blade lower portions 4122 and the second stationary blade lower portions 4132 are superposed on one another, a width W1 between the first stationary blade 412 disposed on the trailing side in the rotational direction R of the impeller 3 out of the first stationary blades 412 adjacent to each other and the second stationary blade 413 disposed between the first stationary blades 412 adjacent to each other is preferably 1.1 to 1.3 times a width W2 between the first stationary blade 412 disposed on the leading side in the rotational direction R of the impeller 3 out of the first stationary blades 412 adjacent to each other and the second stationary blade 413 disposed between the first stationary blades 412 adjacent to each other. This can increase the likelihood of the airflow being guided to parts of the flow passage between the stationary blades positioned on the trailing side in the rotational direction R of the impeller 3. Accordingly, the blowing efficiency can be improved.

Furthermore, in the circumferential direction, in a region where the first stationary blade 412 and the second stationary blade 413 are superposed on one another, the center of each of the second stationary blades 413 is disposed at the center of the width between the first stationary blades 412 adjacent to each other. This allows parts of the flow passage between the stationary blades to be uniform as much as possible. Accordingly, the blowing efficiency can be improved.

Furthermore, the axial length between the upper ends of the first stationary blades 412 and the upper ends of the second stationary blades 413 is smaller than the length of the gap in the circumferential direction between the upper ends of the first stationary blades 412 adjacent to each other in the circumferential direction. Thus, the gaps between the upper ends of the first stationary blades 412 are increased in the circumferential direction. This increases the sectional area of parts of the flow passage between the first stationary blades 412. Accordingly, more air can be guided to the parts of the flow passage between the first stationary blades 412.

Furthermore, the axial length of the region where the first stationary blades 412 and the second stationary blades 413 are superposed on one another in the circumferential direction is preferably 0.5 to 0.8 times the axial length of the first stationary blades 412. Accordingly, the blowing efficiency can be improved.

Furthermore, the axial length of the second stationary blades 413 is larger than the axial length of the first stationary blades 412. Thus, with the second stationary blades 413 having a large length, the air is smoothly guided along the second stationary blades 413 also on the lower side of the flow passage. This can reduce the likelihood of generation of turbulent flow, and accordingly, the blowing efficiency can be improved.

As has been described, the vent holes 411A are provided in the upper housing 41. The vent holes 411A penetrate through the upper housing 41 in the radial direction so as to allow communication between the flow passage FL and the inside of the upper housing 41. As illustrated in FIG. 5, the vent holes 411A are disposed immediately below the specified first stationary blades 412.

Part of the air having flowed through the flow passage FL and been regulated by the first stationary blades 412 and the second stationary blades 413 passes through the vent holes 411A and flows into the motor housing 4 (FIG. 4). The air having flowed into the motor housing 4 flows upward into a space disposed further to the upper side than the stator 51. The air having flowed into this space flows downward and passes through the gaps formed in the stator 51 such as gaps between the teeth so as to be exhausted through the outlets 42A of the lower housing 42. This reduces likelihood of heat of the stator 51 being stored in the motor housing 4. Accordingly, efficiency for cooling the stator 51 can be improved.

That is, the motor housing 4 has the vent holes 411A, which penetrate through the upper housing 41 in the radial direction so as to allow communication between the flow passage FL and the inside of the motor housing 4. Accordingly, efficiency for cooling the motor 5 can be improved.

As has been described, the cleaner 100 according to the present embodiment includes the above-described fan 1. This allows the cleaner exhibiting improved blowing efficiency can be realized. Devices in which the fan is mounted are not limited to cleaners. The fan may be mounted in any of a variety of, for example, office automation devices, medical devices, transport devices, and home appliances other than the cleaners.

The above-described embodiment can be modified in various manners without departing from the gist of the present disclosure.

The present disclosure can be utilized for, for example, a fan for a cleaner.

Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.

While preferred embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims. 

What is claimed is:
 1. A fan comprising: an impeller rotated about a vertically extending central axis; a motor rotating the impeller; a motor housing housing the motor; a fan casing disposed radially outside the motor housing so as to form a flow passage in a gap therebetween; a plurality of first stationary blades disposed radially outside the motor housing, the plurality of first stationary blades arranged in a circumferential direction, the plurality of first stationary blades extending in an axial direction; and at least one second stationary blade disposed radially outside the motor housing, the at least one second stationary blade disposed between the first stationary blades adjacent to each other in the circumferential direction out of the plurality of first stationary blades, the at least one second stationary blade extending in the axial direction, the plurality of first stationary blades and the at least one second stationary blade being disposed such that an upper end of the at least one second stationary blade is disposed further to a lower side than upper ends of the plurality of first stationary blades and further to an upper side than a lower ends of the plurality of first stationary blades.
 2. The fan according to claim 1, wherein a lower end of the at least one second stationary blade is disposed further to the lower side than the lower ends of the plurality of first stationary blades.
 3. The fan according to claim 1, wherein, when seen in the axial direction, at least one of the plurality of first stationary blades is partially superposed on the at least one second stationary blade.
 4. The fan according to claim 1, wherein at least part of the motor is in direct or indirect contact with the motor housing, and wherein the plurality of first stationary blades and the at least one second stationary blade are formed of metal.
 5. The fan according to claim 1, wherein the at least one second stationary blade includes a plurality of second stationary blades, and wherein a number of the plurality of first stationary blades is equal to a number of the plurality of second stationary blades.
 6. The fan according to claim 1, wherein, in the circumferential direction, a thickness of the at least one second stationary blade is smaller than a thickness of the plurality of first stationary blades.
 7. The fan according to claim 6, wherein a first lower curved surface curved toward a leading side in a rotational direction of the impeller as the first lower curved surface extends downward is formed in a lower end portion of a first pressure surface of each of the plurality of first stationary blades, wherein a second lower curved surface curved toward the leading side in the rotational direction of the impeller as the second lower curved surface extends downward is formed in a lower end portion of a second pressure surface of the at least one second stationary blade, and wherein a radius of curvature of the second lower curved surface is larger than a radius of curvature of the first lower curved surface.
 8. The fan according to claim 7, wherein the radius of curvature of the second lower curved surface is 1.8 to 2.5 times the radius of curvature of the first lower curved surface.
 9. The fan according to claim 1, wherein the plurality of first stationary blades each include a first stationary blade upper portion inclined toward the circumferential direction toward a trailing side in a rotational direction of the impeller as the first stationary blade upper portion extends from a lower side toward an upper side, and a first stationary blade lower portion positioned further to the lower side than the first stationary blade upper portion in the axial direction, and wherein the at least one second stationary blade includes a second stationary blade upper portion inclined toward the circumferential direction toward the trailing side in the rotational direction of the impeller as the second stationary blade upper portion extends from the lower side toward the upper side, and a second stationary blade lower portion positioned further to the lower side than the second stationary blade upper portion in the axial direction.
 10. The fan according to claim 9, wherein the first stationary blade upper portion has a first curved surface curved further toward the trailing side than the first stationary blade lower portion in the rotational direction of the impeller, and the second stationary blade upper portion has a second curved surface curved further toward the trailing side than the second stationary blade lower portion in the rotational direction of the impeller.
 11. The fan according to claim 10, wherein a length in the circumferential direction between a trailing end of the first stationary blade in the rotational direction of the impeller and a leading end of a first pressure surface in the first stationary blade upper portion in the rotational direction of the impeller is larger than a length in the circumferential direction between a trailing end of the at least one second stationary blade in the rotational direction of the impeller and a leading end of a second pressure surface in the second stationary blade upper portion in the rotational direction of the impeller.
 12. The fan according to claim 10, wherein a radius of curvature of the first pressure surface in the first curved surface is smaller than a radius of curvature of the second pressure surface in the second curved surface.
 13. The fan according to claim 12, wherein the radius of curvature of the second pressure surface in the second curved surface is 1.8 to 2.2 times the radius of curvature of the first pressure surface in the first curved surface.
 14. The fan according to claim 9, wherein the second stationary blade lower portion has an extended surface extending in the axial direction on a second pressure surface side at a position further to the lower side than the lower end of the first stationary blade.
 15. The fan according to claim 14, wherein the first stationary blade lower portion has a first surface that extends in the axial direction on a first pressure surface side, wherein the second stationary blade lower portion has a second surface that extends in the axial direction on the second pressure surface side, and wherein, an axial length of the first surface is smaller than an axial length of the second surface.
 16. The fan according to claim 1, wherein, in the circumferential direction, in a region where the plurality of first stationary blades and the at least one second stationary blade are superposed on one another, a center of the at least one second stationary blades is disposed at a center of a width between the first stationary blades adjacent to each other.
 17. The fan according to claim 1, wherein, an axial length between the upper ends of the plurality of first stationary blades and the upper end of the at least one second stationary blade is smaller than a length of a gap in the circumferential direction between the upper ends of the first stationary blades adjacent to each other in the circumferential direction.
 18. The fan according to claim 1, wherein an axial length of the at least one second stationary blade is larger than an axial length of the plurality of first stationary blades.
 19. The fan according to claim 1, wherein the motor housing has a vent hole that penetrates therethrough in the radial direction so as to allow communication between the flow passage and an inside of the motor housing.
 20. A cleaner comprising: the fan according to claim
 1. 